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Trojans - (Elham Naseri)
What is a computer trojan? Definition: '''Named after the Trojan Horse of ancient Greek history, a '''trojan is a network software application designed to remain hidden on an installed computer. Trojans generally serve maliciious purposes and are therefore a form of malware, like viruses. Trojans sometimes, for example, access personal information stored locally on home or business computers, then send these data to a remote party via the Internet. Alternatively, trojans may serve merely as a "backdoor" application, opening network ports to allow other network applications access to that computer. Trojans are also capable of launching Denial of Service (DoS) attacks. A combination of firewalls and antivirus software protect networks against trojans. Trojans are similiar to worms. In contrast to worms and viruses, however, trojans do not replicate themselves or seek to infect other systems once installed on a computer. Mostly people confuse the term computer Trojan with computer virus. They think that both of these are same. No doubt they both infect your computer but they both have slightly different characteristics. Trojan is a malicious program that cannot replicate itself like the computer virus but can cause serious security problems. It appears as a useful program but in reality it has a secret code that can easily access your system. ITâ€™S NAME Trojan got its name after ancient Trojans. During Siege of Troy ancient Trojans believed that the large wooden horse left behind by the Greeks outside the gates was a sign that after years of war they now wanted peace because the Greeks were losing the war. The Trojans accepted that gift and brought it inside their city. The Greek soldiers were inside that horse. During night they opened the main door so that more soldiers could come inside the city and they could easily attack on the Trojans. Similarly a computer Trojan appears something else but in reality it harms your system. FUNCTIONS OF TROJAN 1)It creates backdoor to your computer which allows the hacker to do anything on your system or we can say that the hacker will get control on your system without your permission. He can see your e-mails, record keystrokes, access password protected accounts and can get any type of information about your computer. 2)It can do malicious functions like rebooting your computer or deleting files. 3)It also installs spyware which takes you to the unwanted sites. 4)Some annoying Trojans can change desktop or add silly active desktop icons. HOW TROJANS CAN SPREAD Hidden in programs They remain hidden in the programs that appear useful because when you download a program from a site you think that this program will be useful but instead it contains Trojan. When you run that program your computer gets infected. Through e-mails Trojans also spread through e-mails. Attacker sends you an email attachment which has executable file. When you open that attachment the Trojan inside it will infect your system. For e.g.:- there is a file â€œcool_girls.txt.exeâ€. â€œtxtâ€ shows that it is a text file and â€œexeâ€ shows that this executable file has the extension. Sometimes you may not notice about â€œexeâ€ and take it as only a text file. When you open this file your system gets infected. Some users use the operating system that even allows hiding these extensions so that the file appears a harmless file and it will look as â€œcool_girls.txtâ€ Chat By sending or receiving files from an unknown person on MSN, yahoo messenger, AIM etc may infect your system with Trojans. Image files Another tactics of spreading Trojan is by embedding it in some image files. Do not open an image file from an unknown person or even from known person when the arrival of file is unexpected. Operating system vulnerabilities It also spreads through operating system vulnerabilities because some Parts that connect computer to the internet have security risk.